Test strips are often used for qualitative and quantitative analysis of blood components. The test strips are sometimes constructed so that the sample application area and the detection area are stacked above one another in a vertical axis. However, this type of construction is associated with a number of problems. For example, when the test strip is inserted into an instrument for measurement, the potentially infectious sample material may contact parts of the optical reader and result in contamination. Thus, spatial separation between the sample application area and detection zone is often desired, i.e., lateral flow strips. Most conventional lateral flow strips are designed for test samples that are readily available in large quantities (e.g., urine). However, when the test sample is blood, the collection of a large sample may cause undue pain to the patient. Thus, one technique that has been utilized to accommodate smaller test sample volumes is to “spot” the sample directly only the membrane surface. Thereafter, a diluent is used to wash away the test sample and carry it to the detection zone. Unfortunately, variations associated with sample transfer and diffusion of the sample to the membrane result in a flow that is largely uncontrolled and uneven before reaching the detection zone. This may have an adverse affect on the accuracy of the device because the amount of analyte and/or label captured across the detection zone is not consistent at the time of measurement.
As such, a need currently exists for a simple and efficient technique for metering a low volume test sample to a detection zone of a lateral flow assay device.